President Donald Trump has repeatedly advocated for a steel slat design for his border wall, which he described as "absolutely critical to border security" in his Oval Office address to the nation Tuesday. But Department of Homeland Security testing of a steel slat prototype proved it could be cut through with a saw, according to a report by DHS.

A photo exclusively obtained by NBC News shows the results of the test after military and Border Patrol personnel were instructed to attempt to destroy the barriers with common tools.

The Trump administration directed the construction of eight steel and concrete prototype walls that were built in Otay Mesa, California, just across the border from Tijuana, Mexico. Trump inspected the prototypes in March 2018. He has now settled on a steel slat, or steel bollard, design for the proposed border barrier additions. Steel bollard fencing has been used under previous administrations.

However, testing by DHS in late 2017 showed all eight prototypes, including the steel slats, were vulnerable to breaching, according to an internal February 2018 U.S. Customs and Border Protection report.

Photos of the breaches were not included in a redacted version of the CBP report, which was first obtained in a Freedom of Information Act Request by San Diego public broadcaster KPBS.

The photo of testing results obtained by NBC News was taken at the testing location along the California-Mexico border, known as "Pogo Row."

Responding to the picture from the South Lawn of the White House on Thursday morning, Trump claimed "that’s a wall designed by previous administrations."

While it is true that previous administrations used this design, the prototype was built during his administration.

"It's very, very hard — the wall that we are doing is very, very hard to penetrate," Trump said.

NBC News toured the eight wall prototypes twice before President Trump's March 2018 inspection. According to San Diego Sector Border Patrol Chief Rodney Scott, the versions seen by NBC News and the president, however, were larger than the actual prototypes tested at "Pogo Row."

In a statement, DHS Spokeswoman Katie Waldman said, "The steel bollard construction is based on the operational requirements of the United States Border Patrol and is a design that has been honed over more than a decade of use. It is an important part of Border Patrol's impedance and denial capability."

"While the design currently being constructed was informed by what we learned in the prototypes, it does not replicate those designs," said Waldman. "The steel bollard design is internally reinforced with materials that require time and multiple industrial tools to breach, thereby providing U.S. Border Patrol agents additional response time to affect a successful law enforcement resolution. In the event that one of the steel bollards becomes damaged, it is quick and cost-effective to repair.

"The professionals on the border know that a wall system is intended not only to prevent entry, it is intended to defer and to increase the amount of time and effort it takes for one to enter so that we can respond with limited border patrol agents. Even a wall that is being breached is a valuable tool in that it allows us to respond to the attempted illegal entry."

In response to KPBS, CBP spokesman Ralph DeSio said the prototypes "were not and cannot be designed to be indestructible," but were designed to "impede or deny efforts to scale, breach, or dig under such a barrier, giving agents time to respond."

In his address to the nation Tuesday, Trump said the steel fence design is "what our professionals at the border want and need. This is just common sense."

As a candidate, Trump promised to build an "impenetrable, physical, tall, powerful, beautiful" wall on the border that would be paid for by Mexico. Before the Oval Office address, the White House's Office of Management and Budget sent a letter to Congress requesting $5.7 billion for the construction of 234 miles of steel barrier.

Amid a government shutdown over his border wall proposal, Trump will travel to McAllen, Texas Thursday to make the case for building the additional border barrier.

"President Trump likes to pretend a wall will solve all our problems, but it's been clear for some time that it is little more than a very expensive vanity project," said Thompson. "Whether steel or concrete, there is nothing special about his wall and it will not secure our borders. Democrats are willing to work with the administration to improve our border security, but let's get back to proven and effective solutions."

Jacob Soboroff

Jacob Soboroff is a correspondent at MSNBC.

Julia Ainsley

Julia Ainsley is a correspondent covering the Department of Homeland Security and the Department of Justice for the NBC News Investigative Unit.